#   Copyright 2017-present Michael Hall
#
#   Licensed under the Apache License, Version 2.0 (the "License");
#   you may not use this file except in compliance with the License.
#   You may obtain a copy of the License at
#
#       http://www.apache.org/licenses/LICENSE-2.0
#
#   Unless required by applicable law or agreed to in writing, software
#   distributed under the License is distributed on an "AS IS" BASIS,
#   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
#   See the License for the specific language governing permissions and
#   limitations under the License.

import html.parser
import re

__all__ = ["html_to_text"]

WhitespaceHandler = re.compile("<p>|<br>|<br />|<li>", flags=re.MULTILINE)

# The below is semi-safe for use here,
# wouldn't reccomend copying this without understanding it.
# html cleanup is taken from https://stackoverflow.com/a/7778368
# with some modifications made to better suit the needs of this.


class HTMLTextExtractor(html.parser.HTMLParser):  # https://stackoverflow.com/a/7778368
    def __init__(self):
        super().__init__()
        self.result = []

    def handle_data(self, d):
        self.result.append(d)

    def get_text(self):
        return "".join(self.result)


def html_to_text(html_data):  # https://stackoverflow.com/a/7778368
    """Converts HTML to plain text (stripping tags and converting entities).
    >>> html_to_text('<a href="#">Demo<!--...--> <em>(&not; \u0394&#x03b7;&#956;&#x03CE;)</em></a>')
    'Demo (\xac \u0394\u03b7\u03bc\u03ce)'

    "Plain text" doesn't mean result can safely be used as-is in HTML.
    >>> html_to_text('&lt;script&gt;alert("Hello");&lt;/script&gt;')
    '<script>alert("Hello");</script>'

    Always use html.escape to sanitize text before using in an HTML context!

    HTMLParser will do its best to make sense of invalid HTML.
    >>> html_to_text('x < y &lt z <!--b')
    'x < y < z '

    Unrecognized named entities are included as-is. '&apos;' is recognized,
    despite being XML only.
    >>> html_to_text('&nosuchentity; &apos; ')
    "&nosuchentity; ' "
    """
    html_data = WhitespaceHandler.sub("\n", html_data)
    s = HTMLTextExtractor()
    s.feed(html_data)
    return s.get_text()